5-44   |   Model 900 ADA / Model 930 Sulfur Pit  Analyzers
Replacing the external Sample Cell RTD:
a.  Wrap a small piece of rubber around the RTD tip, grip the tip with 
channel-lock pliers, and loosen/remove it (counter-clockwise). Use 
short needle-nose pliers to remove the RTD Base from the Upper 
Heater Plate. Carefully pull its wire out from the Seal Body and 
through the Lower Heater Plate only at this time.
IMPORTANT 
When replacing an external RTD, do not remove the RTD wire 
from the Upper Heater Plate at this time.
b.  Assembly the new RTD (P/N 300-4924) and its Base (P/N 300-4914). 
The RTD Base (and RTD Tip, P/N 300-4913) may be reused if not 
damaged.
c.  Pull the faulty RTD out of the Upper Heater Plate approximately 
1", just enough to expose some of the wiring. Cut off the RTD 
head, strip off some insulation, and solder the termination end of 
the new RTD wire to the RTD end of the old RTD wire. Use the old 
wire to pull the new RTD wire through the Upper Heater Plate as 
you remove the old wire. Label the new RTD wire “Sample Cell”.
d.  Apply Loctite 271 (P/N 300-4478) on the small (lower) threads of 
the RTD Base. Rotate the Base counter-clockwise 3–4 turns (take 
care not to over-stress the wire) and then screw (clockwise) the 
Base into the Upper Heater Plate. Hand-tighten the Base. Using 
short needle-nose pliers, tighten the Base until it is snug. Pull the 
RTD wire from the bottom of the Upper Heater Plate, until the RTD 
is seated inside the Base.
e.  Apply Loctite 271 on the large (upper) threads of the Base. Thread 
the RTD Tip clockwise onto its Base and hand-tighten it.
  To protect the Tip, wrap a small piece of rubber around it, lightly 
grip it with channel-lock pliers, and tighten it until it is snug.
f.  Repeat Steps ‘a’ through ‘e’ if replacing the optional Sulfur 
Condenser RTD (if used).
If the Sulfur Condenser RTD is not used, the hole is plugged with a 
Heater Blanking Plug.
NOTE
NOTE